Environmental Impacts of Logging

Environmental Impacts of LoggingTHE WELL-DOCUMENTED environmental impacts of logging167 are
summarised below. Environmental impact assessments of logging operations in a number of
different countries (Papua New Guinea, Solomon Islands and Cameroon, for instance) clearly
demonstrate that destructive logging practices using heavy machinery seriously reduce the
forest's ability to carry out vital environmental and ecological functions.

Watershed Management and Soil Erosion

Forests provide a buffer to filter water and to hold soil in place. They
sustain water and soil resources through recycling nutrients. In watersheds where forests
are degraded or destroyed, minimum flows decrease during the dry season, leading to
drought, while peak floods and soil erosion increase during the wet season. Tributary meets Melinau River, upper reaches of Baram river.
Tributary water (left of picture), from preserved, non-logged and non-eroded watershed.
Water from main river is cloudy with sediment from logging operations.

Flooding along the Baram River in Sarawak has increased significantly since logging
began, the major floods occurring in 1979 and 1981.168 Massive floods, directly
linked to excessive logging, have caused hundreds of deaths in the Philippines169
and Thailand.170

Much of the current logging carried out in Sarawak and other places is on steep lands
dominated by surface materials that are highly susceptible to erosion when disturbed.171
Data collected by the Malaysian Department of Environment in 90 long-term sampling site
locations within 21 river basins has detected incredibly high suspended sediment loads in
most rivers and tributaries. This mainly originates from upstream soil erosion caused by
the indiscriminate construction of logging roads and camps, skid trails and logging
itself.172 Dr Saulei of the University of Papua New Guinea also blames the
logging industry for 'accelerating erosion, weathering and humus decomposition, and
leading to widespread formation of soils with low nutrient and absorptive capacities'.173

A skid track with severe erosion. More than a metre of topsoil
has been lost and the bedrock exposed along many metres of this skid track on Isabel
Island, Solomon Islands (see Kumpulan Emas, page 44).

The scale of inputs of mobilised sediment is clearly seen in this photograph
where many tonnes of material are being made transportable from machinery-mediated topsoil
disturbance and the loss of vegetative cover and litter layers.

Local Climate Regulation

Beside the implications of large-scale logging for global warming, drastic
changes in precipitation are direct and immediate when the forest cover is removed.174
Changes in transpiration result in a greater intensity of tropical rainfall, enhancing
both run-off and erosion, even if the total amount of rainfall remains unchanged. Forest
loss can also make rainfall more erratic, thus lengthening dry periods.175

Forest Fires

Most of the destructive forest fires that have recently raged out of
control across the world, from the Amazon to Indonesia, are widely acknowledged to have
been either started by and/or exacerbated by logging and agricultural development
companies, such as the oil palm industry. One of the most detailed studies on the effects
of fires in Kalimantan, Indonesia, concludes that the considerable decrease in foliage and
related changes in the stand structure, increase of albedo, and horizontal and vertical
air movements caused by fires, may produce significant and lasting effects on the regional
climate.176

Impacts on the Marine Environment

Unsustainable logging mobilises debris that not only finds its way into the
streams and rivers but also to the marine environment, where it damages mangroves and
coral reefs, habitats crucial for aquatic life. In the Solomon Islands, the unique Marovo
Lagoon, a proposed World Heritage Site, is threatened by the ecologically-destructive
logging operations occurring in the surrounding forests. In Papua New Guinea, coral reefs
have been destroyed to construct log ponds.

Loss of Biodiversity

Logging often destroys natural habitats, resulting in the loss of
biodiversity and sometimes leading to the local, and possibly global, extinction of
species. Although estimates of the rates of loss vary, few deny the reality of the current
losses of both flora and fauna.177

According to a joint report by the Worldwide Fund for Nature and the Sarawak Forest
Department, "Logging causes immediate forest disturbances, long-term habitat
changes (e.g. damage to food trees and salt-licks), increased hunting by timber company
workers and availability of logging roads as hunting routes. The destruction of wildlife
from habitat loss must be recognised to be on an enormous scale".178
In Central Africa, the opening-up of the forest by logging facilitates the illegal hunting
of wildlife, including protected species such as primates, and is leading to a decline in
wildlife populations.179 Deterioration in water quality has caused a decline in
fish stocks and has affected aquatic biological diversity because indigenous animals and
plant life are highly vulnerable to oxygen depletion, suspended particulate matter and a
lack of light.180

Even so called selective logging severely affects the complex and rich biodiversity of
forests through excessive damage to residual stands, destruction of other plant and tree
species and the creaming-off of species which are the most valuable for timber. An FAO
study in Malaysia has shown that as much as 50% of the standing forest may be damaged and
the surface soil destroyed when up to 30% of the ground surface is exposed. During
silvicultural treatment in logging operations in Sarawak, so-called uneconomic forest
species are deliberately poisoned. This reduces the complexity and species diversity of
the tropical forests to only 10% of the original condition, resulting in the systematic
elimination of tree genetic resources and contamination of the environment.181
According to the IUCN the most frequently recorded of all threats to globally endangered
tree species is 'felling'.182